1. Field of the Invention
The present invention relates to a pipe joint enabling the connection of pipes for introduction and discharge of fluids therethrough, and more specifically to a pipe joint equipped with a socket and plug attachment/detachment mechanism.
2. Description of the Related Art
Heretofore, a pipe joint equipped with an attachment/detachment mechanism facilitating detachment of a socket and plug has been used. With such a pipe joint, in a state in which the socket and plug are detached from each other, so that fluid does not flow outwardly therefrom, both the socket and plug sides are equipped with check valves therein. Thus, when the socket and plug are detached from each other, the check valves assume valve-closed states, so that leakage of fluid to the outside is prevented. (See, Japanese Utility Model Publication No. 47-42011, Japanese Laid-Open Utility Model Publication No. 62-13289, and Japanese Laid-Open Patent Publication No. 2003-202096.)
However, in the conventional art described in Japanese Utility Model Publication No. 47-42011 and Japanese Laid-Open Utility Model Publication No. 62-13289 and Japanese Laid-Open Patent Publication No. 2003-202096, the flow passage through which the fluid flows is guided radially outwardly from a side of the connecting end of the plug and is divided into a plurality of flow passages. Thereafter, the flow passage is guided radially inwardly through an annular flow passage, changing once again radially outwardly while being divided into a plurality of passages, and is connected to the connecting end side of the socket. In the case of such a complex flow passage shape, the fluid flows through the pipe joint while colliding against wall surfaces perpendicular to the flow direction of the fluid as well as against wall surfaces that are inclined with respect to the flow direction, and as a result, fluid passage resistance becomes large, the flow direction of the fluid becomes disturbed, and pressure loss occurs.
Further, in the conventional art described in Japanese Utility Model Publication No. 47-42011, Japanese Laid-Open Utility Model Publication No. 62-13289 and Japanese Laid-Open Patent Publication No. 2003-202096, because a structure is provided equipped with a spring on an inner circumferential side of a sleeve, the outer circumferential diameter of the sleeve is enlarged to accommodate the spring portion, and together therewith, the pipe joint tends to become increased in size overall.
Furthermore, when the check valves are assembled in the interior of the socket and plug, since the check valves are inserted into the interior from sides of the connection ends of the socket and plug respectively, a limitation is placed on the size of the check valves that can be assembled therein owing to the opening diameters of the connection ends, such that check valves having desirable sizes cannot be assembled therein.